A toner image which has been formed by electrophotography or the like is irreversibly fixed by a fixing procedure to obtain a hard copy. An irreversible fixing process utilizing heat is called "heat fixing process". An irreversible fixing process utilizing pressure alone is called "pressure fixing process". Examples of the heat fixing process include fixing process in which fixing is effected in a non-contact system such as oven fixing process and radiant heating process, fixing process in which fixing is effected in contact with toner images under some pressure such as heat roll fixing process, and fixing process in which light energy is absorbed by a toner to heat and fix the toner such as flash fixing process.
Such a heat fixing process is disadvantageous in that it consumes a considerably large amount of electric power. For example, even the heat roll fixing process, which provides a relatively good thermal efficiency, consumes at its fixing step about half the power consumption of the entire electrophotographic system. It goes without saying that if the toner is molten at a low temperature, the power consumption of the fixing system can be lowered. However, this approach deteriorates the preservability of the toner, causing toner blocking or the like.